Ortega-Jimenez Victor M, Yee Tien, Rohilla Pankaj, Seleb Benjamin, Belair Jake, Bhamla Saad
Department of Integrative Biology, University of California, Berkeley, CA 94720.
School of Biology and Ecology, University of Maine, Orono, ME 04469.
Proc Natl Acad Sci U S A. 2025 May 27;122(21):e2503495122. doi: 10.1073/pnas.2503495122. Epub 2025 May 12.
Flamingos feature one of the most sophisticated filter-feeding systems among birds, characterized by upside-down feeding, comb-like lamellae, and a piston-like tongue. However, the hydrodynamic functions of their L-shaped chattering beak, S-curved neck, and distinct behaviors such as stomping and feeding against the flow remain a mystery. Combining live flamingo experiments with live brine shrimp and passive particles, bioinspired physical models, and 3D CFD simulations, we show that flamingos generate self-induced vortical traps using their heads, beaks, and feet to capture agile planktonic prey in harsh fluid environments. When retracting their heads rapidly (40 cm/s), flamingos generate tornado-like vortices that stir up and upwell bottom sediments and live shrimp aided by their L-shaped beak. Remarkably, they also induce directional flows (7 cm/s) through asymmetric beak chattering underwater (~12 Hz). Their morphing feet create horizontal eddies during stomping, lifting, and concentrating sediments and brine shrimp, while trapping fast-swimming invertebrates, as confirmed by using a 3D-printed morphing foot model. During interfacial skimming, flamingos produce a vortical recirculation zone at the beak's tip, aiding in prey capture. Experiments using a flamingo-inspired particle collection system indicate that beak chattering improves capture rates by ~7×. These findings offer design principles for bioinspired particle collection systems that may be applied to remove pollutants and harmful microorganisms from water bodies.
火烈鸟拥有鸟类中最为复杂的滤食系统之一，其特点是倒立进食、梳状薄片以及活塞状舌头。然而，它们呈L形的开合喙、S形的脖子以及诸如跺脚和逆流进食等独特行为的流体动力学功能仍是个谜。我们将火烈鸟活体实验与活体盐水虾和被动颗粒、仿生物理模型以及三维计算流体动力学模拟相结合，发现火烈鸟利用其头部、喙和脚产生自诱导涡旋陷阱，以便在恶劣的流体环境中捕获敏捷的浮游猎物。当火烈鸟快速缩回头部（约40厘米/秒）时，它们会产生类似龙卷风的涡旋，借助其L形喙搅动并使底部沉积物和活虾上升。值得注意的是，它们还通过水下不对称的喙开合（约12赫兹）诱导定向水流（约7厘米/秒）。它们变形的脚在跺脚、抬起以及集中沉积物和盐水虾的过程中产生水平涡流，同时捕获快速游动的无脊椎动物，这一点通过使用3D打印的变形脚模型得到了证实。在水面掠过进食时，火烈鸟在喙尖处产生一个涡旋再循环区，有助于捕获猎物。使用受火烈鸟启发的颗粒收集系统进行的实验表明，喙的开合使捕获率提高了约7倍。这些发现为仿生颗粒收集系统提供了设计原理，可应用于从水体中去除污染物和有害微生物。
